docs: def get_mean_and_stddevs(self, sites, rup, dists, imt, stddev_types):
          """
          See :meth:`superclass method
          <.base.GroundShakingIntensityModel.get_mean_and_stddevs>`
          for spec of input and result values.
          """
          # extract dictionaries of coefficients specific to required
          # intensity measure type and for PGA
          C = self.COEFFS[imt]
          C_PGA = self.COEFFS[PGA()]
  
          # Get mean and standard deviation of PGA on rock (Vs30 1100 m/s^2)
          pga1100 = np.exp(self.get_mean_values(C_PGA, sites, rup, dists, None))
          # Get mean and standard deviations for IMT
          mean = self.get_mean_values(C, sites, rup, dists, pga1100)
          if imt.name == "SA" and imt.period <= 0.25:
              # According to Campbell & Bozorgnia (2013) [NGA West 2 Report]
              # If Sa (T) < PGA for T < 0.25 then set mean Sa(T) to mean PGA
              # Get PGA on soil
              pga = self.get_mean_values(C_PGA, sites, rup, dists, pga1100)
              idx = mean <= pga
              mean[idx] = pga[idx]
          # Get standard deviations
          stddevs = self._get_stddevs(C,
                                      C_PGA,
                                      rup,
                                      sites,
                                      pga1100,
                                      stddev_types)
          return mean, stddevs